Radio active dating
Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object.
The amount of carbon-14 in the atmosphere has not changed in thousands of years.
Other dating methods (using the uranium-thorium ratio, for example) reveal the amount by which the carbon 14 results need to be corrected.
For instance, the correction is an approximate 3,000 years increase, for ages of the order of 20,000 years,.
As the rock gets older the proportion of lead increases.
If half of the uranium-238 has turned into lead-206 the rock will be 4500 million years old.
This means all living things have radioactive carbon-14 in them.
When an organism, eg a tree, dies it stops taking in carbon dioxide.
In the radioactivity hourglass upper part, that gradually empties, are decaying nuclei.Many isotopes have been studied, probing a wide range of time scales.C and counting the amount of each) allows one to date the death of the once-living things.The half-life of uranium-238 is 4500 million years.When it decays it forms thorium-234 which is also unstable.